Given the task definition and input, reply with output. In this task, you're given a context passage. Your job is to generate relevant questions that can be answered by directly referring to the passage.

I think she is probably in a great deal of pain , as she is sleeping a lot . She also appears frustrated at having to re - learn how to walk , especially when she is sleepy . The vet has been closed since we picked her up Wednesday , so tomorrow we will call and see if she should be on pain medication . She does better when she finally wakes up at walking about , but she's been sleeping really heavily lately and frequently prefers to go back to sleep to waking up .

What may have caused her to start sleeping a lot ?